Brother LH4-B800E Service Manual download pdf (Page 88)

LH4-B800E

4 - 1

4. Adjustment

(a)

(b)

(c)

4. ADJUSTMENT

[When turning on the power to make adjustments]

1. Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the

presser foot before carrying out adjustments.

“Adj” will appear in the numeric display and the machine will not operate even if the treadle is pressed.

* Some items are adjusted without the RESET key being pressed. Carry out the adjustment by following the

explanations given.

[When turning off the power to make adjustments]

* Do not force any of the parts to move, as doing so may result in damage to the parts.

1. Be sure to turn the machine pulley to raise the needle bar to its highest position before making adjustments.

* If this is not done, the pulley position (the direction of rotation of the rotary hook) may cause the lower thread

trimmer mechanism to touch the rotary hook when the lower thread trimmer mechanism operates.

2. When turning the machine pulley, do it at a position where the thread trimmer mechanism will not operate (the

position where the presser foot pulse motor is at the home position).

* If the machine pulley is turned at a position where the thread trimmer mechanism operates, the needle may

touch the lower thread trimmer mechanism (lower thread retainer and lower thread trimmer knife).

* If the machine pulley is turned at a position where the thread trimmer mechanism operates, the rotary hook

and the lower thread trimmer mechanism may touch.

3. When moving the feed mechanism, do it at a position where the thread trimmer mechanism will not operate (the

position where the presser foot pulse motor is at the home position).

* If this is not done, the lower thread retainer and the feed guide shaft may alternately push against the lower

thread clamp and the opening plate, and damage may result.

4. When pushing the knife down by hand, be careful not to let it touch the upper thread scissors.

5. Do not move the feed mechanism while the stop plate of the upper thread trimmer lever is pulled forward and the

upper thread scissors are open (the upper thread trimmer lever is pushed to the left).

Always return the stop plate to its original position before moving the feed mechanism or returning it to the home

position.

Notes on making adjustments

Fig. A

Fig. B

Fig. C

Pulled forward

Presser foot lifter pulse motor and feed pulse motor home

position (sewing start position)

When the stop plate w of the upper thread trimmer lever

q is pulled forward from the position in diagram (A), the

upper thread trimmer assembly e moves in the direction

of the arrow (a) and goes below the projection of the open-

ing cam r.

Them when the feed mechanism is operated (arrow (c)),

the scissors assembly e is forced to go behind the open-

ing cam r. Depending on the case, the rising section y

of scissors M t goes into the hollow shown in the dia-

gram and the feed mechanism cannot then operate. At

this time, when feed mechanism home positioning is car-

ried out, the feed pulse motor goes out of step.

* Operate the feed mechanism when the condition is

as shown in diagram A.

If it is pushed in the direction of arrow (b) at the condi-

tion shown in diagram B, the condition will change to

that shown in diagram A.

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Brother LH4-B800E Service Manual Page 88

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